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 Post subject: cam changes
PostPosted: Wed Oct 23, 2013 3:58 pm 
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Turbo Slant 6

Joined: Thu Jan 04, 2007 6:38 pm
Posts: 878
Location: Boulder City Nevada
Car Model:
So I'm putting together a street/strip 64 Dart together with a bunch of leftover parts that I have laying around.
The engine I have is a stock bore and piston 67 225 with a head milled .100 and mild port work,stock valve size.Clifford intake and a 500 AFB.Clifford shorty headers.
The cam is a Comp part#64-000-5 Grind#cr6 5667/5668 s 108+4
Lift .424 I&E Duration at .050 I 230 E 238
Lobe separation 108
So it has a 4 degree advance built in. I'm thinking of changing the degreeing and have heard that some of you like to retard several degrees. This car will be about about 5 to 600 pounds lighter than the (67 Dart 3200+ lbs) the engine was in.
I'm also planning on running 2.94 gears to a maximum of 3.55's.Most likely will run the 2.94's because everything is high speed highways around here.Average speeds between 65 to 80 mph just to keep up with traffic.The car will have a Hughes locking converter with a stall of 2200 rpm.
Any thoughts on which way to go or leave the cam the way it is.??


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 Post subject:
PostPosted: Wed Oct 23, 2013 4:12 pm 
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Guru
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Joined: Mon Oct 14, 2002 4:32 pm
Posts: 4880
Location: Working in Silicon Valley, USA
Car Model:
Does the cam card define the Intake Valve closing point? (IC)
With the IC number we can calculate the DCRs at different cam advance / retard positions.
DD


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 Post subject:
PostPosted: Wed Oct 23, 2013 4:32 pm 
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Turbo Slant 6

Joined: Thu Jan 04, 2007 6:38 pm
Posts: 878
Location: Boulder City Nevada
Car Model:
Thanks Doc, Here ya go,,,
Valve timing Open Close
At .050 I 11 BTDC 39 ABDC
E 51 BBOC 7 ATOC


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 Post subject:
PostPosted: Wed Oct 23, 2013 4:33 pm 
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Turbo Slant 6

Joined: Thu Jan 04, 2007 6:38 pm
Posts: 878
Location: Boulder City Nevada
Car Model:
Sorry if hard to read, It didn't post the way I typed it.


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 Post subject:
PostPosted: Wed Oct 23, 2013 5:05 pm 
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Guru
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Joined: Mon Oct 14, 2002 4:32 pm
Posts: 4880
Location: Working in Silicon Valley, USA
Car Model:
The 39 IC is the important piece of the puzzle.
The other "unknowns ar the actual hed cc's (45?) and the block deck. (-180?)

With those estimates and a .020 head gasket, the static cr is 9.2 and the DCR is 7.92

Confirm the head cc's and deck so you can dial-in the DCR with that cam.
Doug


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 Post subject:
PostPosted: Wed Oct 23, 2013 6:13 pm 
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Turbo Slant 6

Joined: Thu Jan 04, 2007 6:38 pm
Posts: 878
Location: Boulder City Nevada
Car Model:
The head cc'd at 44. The head gasket .039 Block has the factory deck height as the short block has never been apart.


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 Post subject:
PostPosted: Thu Oct 24, 2013 4:31 am 
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Supercharged

Joined: Sun Jun 04, 2006 4:53 pm
Posts: 4295
Location: Gaithersburg MD
Car Model:
You guys sure impress me with your smarts. That is not a smart-a** comment. I mean it.

Sam

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 Post subject:
PostPosted: Thu Oct 24, 2013 7:41 am 
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Turbo Slant 6

Joined: Thu Jan 04, 2007 6:38 pm
Posts: 878
Location: Boulder City Nevada
Car Model:
Sam, I'm dumber than a doughnut when it comes to numbers. Just reading what I found in the file from when I first started working on the 67 about 20 years ago. The engine was modified around '96 to keep up with the drivers on the Hot Rod Power Tour. It's been sitting in the corner for the last 10 years. So I thought to call the Dart "Leftovers". We will see how it turns out.


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 Post subject:
PostPosted: Thu Oct 24, 2013 9:09 am 
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Guru
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Joined: Mon Oct 14, 2002 4:32 pm
Posts: 4880
Location: Working in Silicon Valley, USA
Car Model:
So the deck height is the big unknown here...
("Stock" does not mean much seeing the factory was "all over the map" with this number)

Cut to the chase....
Measure the deck and set that at -.160 (may need a "clean-up" cut)
Set that cam so the IC is 54 ABDC. (Straight-up) Check the IC at .016 lash.
Doing that will get you a 9.3 CR and a 8.015 DCR.
DD


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 Post subject:
PostPosted: Thu Oct 24, 2013 3:29 pm 
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Turbo Slant 6

Joined: Thu Jan 04, 2007 6:38 pm
Posts: 878
Location: Boulder City Nevada
Car Model:
O KEY DOO KEY ! Thanks


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 Post subject:
PostPosted: Sun Oct 27, 2013 6:10 am 
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Supercharged

Joined: Sun Jun 04, 2006 4:53 pm
Posts: 4295
Location: Gaithersburg MD
Car Model:
Is the difference between compression ratio and dynamic compression ratio result from the losses at overlap?

And a dummy question: What is ABDC.? Thanks. Sam

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 Post subject:
PostPosted: Sun Oct 27, 2013 8:06 am 
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EFI Slant 6
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Joined: Thu Jul 24, 2008 11:37 am
Posts: 411
Location: Brooklyn, NY
Car Model: 1964 Valiant V200
Quote:
Is the difference between compression ratio and dynamic compression ratio result from the losses at overlap?

And a dummy question: What is ABDC.? Thanks. Sam

Dynamic compression ratio isn't really an accurate term but people use it anyway. What they really mean is 'Effective' static compression ratio, which is the compression ratio calculated from the point the intake valve closes on the compression stroke. So a big intake lobe, or one that is retarded, closes the intake valve as the piston is further up the cylinder. The later the valve closes the less effective compression the engine has.

That's why a big cam can use more compression without pinging on the same fuel.

Overlap could be more or less with the same DCR depending on how far apart the lobes are ground.

ABDC = After Bottom Dead Center (on the compression stroke).


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 Post subject:
PostPosted: Sun Oct 27, 2013 2:43 pm 
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Turbo Slant 6

Joined: Thu Jan 04, 2007 6:38 pm
Posts: 878
Location: Boulder City Nevada
Car Model:
I'm working on getting the deck height figure to finish the equation Doc has started.


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 Post subject:
PostPosted: Wed Oct 30, 2013 6:52 am 
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Turbo Slant 6

Joined: Thu Jan 04, 2007 6:38 pm
Posts: 878
Location: Boulder City Nevada
Car Model:
Doc you were correct as usual,this engine the deck height is .200 max and varies .004 between the 6 cylinders.As you said"All over the place".
As stated before just wondering if I should leave it as is or try retarding if it would make it run better.
I'm calling this car "Leftovers" :wink: as it is being put together with what I have that has been sitting around the shop and on shelves.She won't look like much but will be in great mechanical shape for MATS in April.
This will be my final slanter(maybe) for now.


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 Post subject: Calling on Doc
PostPosted: Sun Nov 03, 2013 6:28 am 
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Turbo Slant 6

Joined: Thu Jan 04, 2007 6:38 pm
Posts: 878
Location: Boulder City Nevada
Car Model:
Just a bump for Doug, Hope ya chime in and help me finish the puzzle with the last spec in the post above. :?:


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